The present invention relates to a phacoemulsification/irrigation and aspiration sleeve apparatus which is useful during the removal of a cataract lens from a human eye.
The concept of implanting an intraocular lens, as a replacement for an opaque or cloudy cataract lens of a human eye, was suggested as early as 1766 by Casanova in his memoirs. It has been only within the last 30 years or so, however, that theory and desire have become a practical reality. In this connection, the first lens implantation is believed to have been carried out in 1949 by Dr. Harold Ridley at the St. Thomas Hospital in London. A lens was inserted into the posterior chamber of the eye of a woman of about 60 years of age following cataract extraction. Dr. Ridley's early efforts achieved a degree of success and ophthalmic surgeons began implanting lens composed of polymethylmethacrylate (PMMA) within the posterior chamber of human eyes following extracapsular removal of cataracts to restore binocular vision to patients.
Although certain drawbacks and complications accompanied successes, the art has continually progressed over the years and in 1982 it has been estimated that 500,000 cataract extractions were performed in the United States alone.
A cataract lens extraction process may be performed by a variety of techniques, however, one extracapsular extraction technique comprises making a 100 to 140 degree incision around the corneal rim of the eye and the lens is removed as a unit by manipulation of a lens loop instrument through a dilated or undilated iris. Although this extracapsular technique has been widely utilized, there has been increased attention in recent years toward another form of extracapsular cataract surgery. In this type of operative procedure, the capsule surrounding the cataract, or cloudy crystalline lens, is opened (usually anteriorly) and the cataract material is evacuated leaving the remainder of the capsular bag intact along with the zonules. This leaves the compartmentalization of the eye essentially intact and contributes to the stability of the eye. Many surgeons believe that this stability results in a lower complication rate which is particularly significant with an increasing frequency of artificial lens-implantation.
In the above connection, an extracapsular technique known as phacoemulsifacation and aspiration has been developed by a Dr. Kelman and his associates wherein an ultrasonic vibrating tip is inserted through a small corneal incision of three millimeters or so. The ultra-sonic tip operably emulsifies the cataract, in situ. A co-axial sleeve extends along the ultrasonic tip and permits a simultaneous infection of a saline flushing solution to suspend particles of lens material and to simultaneously cool the vibrating tip member. The ultrasonic tip is fashioned with an axial bore and a vacuum is drawn on the bore to aspire the emulsified lens material and fluid co-axially through the ultrasonic tip.
Although the Kelman unit has been refined and improved over the years, certain disadvantages persist. In this connection, in order for the ultrasonic probe to exhibit a desired vibratory motion, relatively free from damping, the surrounding sleeve is composed of a soft pliable elastomeric material. It has been found that in some instances of operative procedures, and angles of utilization, the soft sleeve collapses or deflects against the ultrasonic probe. When the sleeve is pushed against the rapidly vibrating probe, the probe and sleeve tend to overheat due to friction and damage the delicate corneal or sclera tissue of the eye. In addition prior sleeves have tended to permit a random non-uniform flow pattern of fluid around the ultrasonic tip such that zones of elevated temperature may develop on the tip.
In addition to phacoemulsification and aspiration, certain instances occur when irrigation and aspiration are desired without concomitant phacoemulsification. In such systems, the central probe does not vibrate, however, it is still important to be able to insure a generally uniform irrigation throughout the range of angular probe manipulation. In the past, relatively pliable sleeves have tended to collapse and block a steady flow of irrigation fluid when a handpiece is manipulated to the right or left.
The difficulties suggested in the proceeding are not intended to be exhaustive, but rather are among many which may tend to reduce the effectiveness and satisfaction with prior phacoemulsification and aspiration devices. Other noteworthy problems may also exist. Those presented above, however, should be sufficient to demonstrate that phacoemulsification and aspiration devices appearing in the past will admit to worthwhile improvement.